1. Field of the Invention
The present invention relates to a head-up display device and a display unit, and in particular, to a technology to guide the sight line of a driver.
2. Description of the Related Art
In general, a head-up display device mounted on a vehicle is configured to project display light emitted from a projector on an optical element (half mirror) called a combiner, and reflect light reflected on a surface of the combiner in a viewing direction of a driver so as to guide the light to a predetermined eye point that is a viewing position of the driver (refer to Japanese Patent Application Laid-open No. 2006-011122, for example). The combiner is disposed in a position, such as on the instrument panel in front of the driver's seat, easily viewed by the driver. A front windshield may be used as the reflective surface of the display light, instead of the combiner.
The head-up display device forms a display image as a virtual image in a position in front of the combiner in the direction of vehicle travel (that is, behind the combiner in the viewing direction), and thereby has an advantage that the driver needs to make only slight focus adjustment to view the display image. The head-up display device also allows viewing of a sight in front of the vehicle viewed through the combiner and the display image formed at the front in the travel direction in an overlapping manner, and thereby can show information in a new way different from that of display using an ordinary display panel.
Such a head-up display device can be used, for example, for displaying the traveling speed of the vehicle. The driver can view the speed display without a large amount of movement of the sight line or focus adjustment while facing forward, so that the head-up display device is suitable for displaying important information, such as the vehicle speed.
While a variety of information can be displayed on the combiner of the head-up display device, there are few cases of showing many pieces of information at a time. For example, when malfunction occurs such as a failure in the vehicle, it is often the case that only a warning indication by a symbol, such as an exclamation mark (!), is displayed, and information, such as a text, to explain the content of the malfunction is not displayed. This is for preventing the driver from being disturbed in driving due to blocking of the field of view of the driver, or diverse attention from the front.
Hence, it is conceivable that, when malfunction occurs, the warning indication is displayed on the combiner, and at the same time, the information, such as a text, to explain the content is displayed on another display section, for example, a meter unit. In general, however, the combiner and the display section, for example, the meter unit, are disposed in positions distant from each other in the up-down and/or the left-right direction(s) (that is, in a direction orthogonal to the viewing direction), so that the driver may not notice that the information to explain the content of the malfunction is displayed on the display section, for example, the meter unit.
While the display section of the meter unit displays the information on a display surface thereof, the virtual image displayed by the head-up display device is formed behind the combiner in the viewing direction, and is viewed by the driver. In other words, the image forming position of the display image in the head-up display device and the display screen of the meter unit are distant from each other in the viewing direction. This may also cause the driver to fail to notice that the information to explain the content of the malfunction is displayed on the display section, for example, the meter unit.
Hence, the sight line needs to be guided from the combiner to the display section, for example, the meter unit to lead the driver who is watching the combiner to view the display section, for example, the meter unit.
The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a head-up display device and a display unit that can easily guide the sight line of a driver.
The object described above according to the present invention is achieved by the following configurations.